Dowel-pin for electrical conduits.



PATENTED JULY 3, 1906.

DOWEL PINPOR BLEO'IiRICAL OONDUITS.

APPLICATION FILED FEB.27.1905.

1; A1 1 P ECE.

Specification of Letters Patent.

Patented July 3, 1906.

Application filed February 27, 1905. Serial No= 247,488.

"To all whom it may concern,- Be it known that I, RALPH S. PEIROE, a

citizen of the United States of America, and

.aresident of Chicago, county of Cook, and

State of Illinois, have invented a new, and useful Improvement in Dowel-Pins for Elec- .-ti ical Conduits, of which the following'is a L conduits.

t5" ,gun'g one or more ducts, this being of vitrified "clay; The clay tile as delivered by the man-.

specification.

invention relates to an improvement in dowehpins for securing the proper alinement between the several sections of material used in the building of underground electrical A large portion of the underground con- .duits' now in use is built of sections of tile havufactur'er is provided at each end with holes for dowel-pins, the holes in the ends of the tion is lia adjoining sections being so located as to register with each other when the tile is in proper position: To secure the proper alinement during the laying of the tile, dowel pins of various forms are used, these being inserted first into the holes of a piece of tile that has been laid in such manner that the protruding ends will enter the in the piece of tile being laid in such manner asto cause the proper registration of the ductor ducts Within the tiles. The dowelpins for this purpose have in the past been made of solid pieces of iron with a shoulder or projection about midway'in their length to assure the dowel-pin projecting a proper distance into each section. In other cases wood pins have been usedfor this purpose.

Both of these forms are ob ectionable for .the following reasons; The solid iron dowelpins are inflexible, and therefore when thrust or driven into a hole in the tile that is through some irregularity too small a cracking of the tile around the hole is caused, which either renders the tile unfit for use or at best roughens the wall of gree. The holes in difleren't tiles of the same lot or of different lots often vary in size, so that a number of different sizes of dowelpins have to be carried in stock to assure proper fitting of the tiles together. Again, a solid iron in of ordinary form and construcle to rust on account of the presence of moisture, and this in such cases has been found to cause such an expansion of the pins or of rust on the pins as to cause the subsequent breakim of the tile and injury of the duct. Still another objection to this form corresponding holes v holes'in the end of this section.

the duct to an undesirable deoverlap each other, jected to compressive stress it will yield and 105 of pin is that it is of considerable weight, which is objectionable in theinutter of transportation, but more so in the handling in the trench. The wooden pins have the advan- 6o tage of being cheap, but are subject to even greater objection in the point of expansion, due to the presence of moisture and to some extent due to excessive rigidity, which in the case of distorted dowel-holes or holes that are out of alinclnent may cause breakage of the tile. Thcseobjections on the part of the types of pins in use at the time of my invention are rendered all the more serious because setting which causes pieces of the inner wall of the ducts to break off and fall within the duct may cause the most serious damage to the cables subsequently to be carried in the of the fact that any breakage of the tile after duct, either in the drawing in or subsequent drawing out of the cable. Sharp pieces of hard burnt clay falling within a duct after a cable had been drawn in may easilyrendcr the subsequent withdrawal of the cable from the duct an impossibility or the lead sheath in the process of withdrawal as to ruin the cable. It is to the remedy of these objectionable features that my present invention is directed.

My invention is illustrated inth'c accompanying sheet of drawings, in whicli Figure 1 is a perspective view of a single section of six-duct clay tile, showing one of my im roved dowel-pins inserted and anot er a out to be inserted in the two dowel- Fig. 2 is a perspective view of a dowel-pin embodying my invention in its preferred form. Fig. 3 is a sectional view of the pin, taken on the line 3 of Fig. 2. modified form of my invention, and Fig. 5 is a sectional view taken on the line 5 of Fig. 4.

As will be seen from the drawings, the dowel-pin embodying my invention is made in tubular form from a piece of sheet metal 100 0, preferably iron rolled up from a flat sheet. The edges 1) and c of the sheet are in the preferred form (shown in Figs. 2 and 3) caused to so" that if the tube is subbecome smaller in diameter, the overlapping sections'sliding by each other in an obvious manner. In this way the pin will adapt itself to almost any size of dowel-hole without causing such strain to come on the walls 1 IO of the tile as to cause breakage.

The ends of the tube are made somewhat smaller by so greatly abrade'8o Fig. 4 is a perspective view of a 5 is little whether or not them in his feature oflig 5 Sure the the holes, such as g,

Fig. '3, thus facilitating the drivingof the dowel-pin'sinto holes of somewhat smaller than standard size and aiding the insertion? of the tube into any size of h Aboi'it midway'in the length'of the tube is a pro'ection'j, preferably struck up from the meta before it. is rolledintotubularform.

rojection,; which may be of any desired orm, serves merely-sea stop in theinserti'on of the pin into theztile, so as to asequal distance in each.

standard piece ofsix-duct clay tile is clearly.

shown in Fig. 1,-the pins ture of the tile, cause the proper re tration of the ducts h mthe two sections, t us formin a continuous duct for the passageof the cales.

As the sections of the tiles' iare lai cl'they are embedded in av m'as's'of concrete., ;suitab le and.we ll known means being taken to. prevent the entrance of concrete or/mortar while in a plastic state .throughffitheinterabutting edges of When so laid and after the constioes formed between the continuous rigid structure, an it matters the'dowel-pins have any subsequent holding force. In fact, it may be stated that the function of the dowel-pin is to assure proper alinement during the laying-of the tile and loses its strength in future no harm is done.

For this reason the pins .madeinaccordance with my invention may be of comparatively thin iron ungalvanized, and when so made are of comparatively 'lcheap construction. Again, the pins. are so light. that'a workman may carry a com aratively large number of 00 et during work, and this tness has an additional advantage in the matter of trans ortation.

The fact that dowel-pinsmad e in accordance with my invention are not rigid as to their size adapts them readily to tile having used, since-the insdowel-holes differing in considerable degree.

as to diameter.

lmperfectly formed holes and holes slightly out of alinement m'a be may be driven in wit out danger of brea age to the duct material.

In 4 and .Jform of dowel-pin "scribed, as I consider-that other forms of 7 those herein specifically illustrated{having fielding. sides would lie thescope of projection of the "pin toabout an ofthe abutting tiles. The methodof applying the dowel-pin to a being inserted into- 'Ini until the stop f engages the face of the tile,'and fromtlns it Wlll be obvious that when .the next section of thetile-is laid in place the projectionof'the ins into the holes 9 of that section will,if t ose adaptable for s' holes are properly located in the mainline that if, it rests through and'. than negligible separation of substantial 5 are shown a modified form able space being left'between them: This ofmy improveddowel-pin, the difl'erencebe= provides for the contractionin the size of the practice. v I

I do not-wish to limit myself'to the exact herein shown and dedowel-pins than;

' 'my invention. For inted sheet metal stance, a pin [of- 1cc e proper degree of 7 ht be used-to secureit Tding when inserted. in the dowel-holes.

a either do-I wishrtd'liniit myself to dowelpins to he used exclusively for the laying of clay .ftile; since :the; doweiepin is obviously ar-purposes in' other arts. 8 Having thus described my invention, what I claim as new, and desire to secure by LettersPatent, is I 1. As an article of manufacture, a tubular dowel-pin having tapered ends and havin at 8 a point in its middlelength a lateral projectimi of a thickness to be negligible in the use of the dowel-pin, substantially as described. 2. As an article of manufacture, a sheetinetal dowelepin having its endstapered and 9 be in a manner that proves satisfactory of sai dowel-pin to'limit'its insertion.

1 3. As an article 0 manufacture, a sheetmetal dowel-pin. for alining sections of tile,

said dowel-pinhaving tapered ends andhav- 9 ing at a point in its middle length a pro'ec' tion struck up from the sheet metal'an of v y as described. =1 4. As an article of manufaptnre, a dcwjel- 3 pin for alining sections of tileconsisting of a sheet of metal rolled into tu ular form, the

adjacent-edges of said sheet along the len' th m va thfiies projecof the tubular dowel-pin being respect to each other, and a lateral tion being struck up from the .sheetmetal ."of;

said tube in the center of said dowel-pin for:-

limiting scribed. I i

Signed by -me atChicago, State of Illinois, nesses.

its insertion, substantially I as :de-

county e f-Cook} 1n the'presence of two wit} .L'RaLPii s. raises." Witnesses: i

' such small thicknesses to produce. not more 1:

the tile ends,i 

